Lubricating oil compositions

ABSTRACT

The present invention generally relates to a method for reducing intake valve deposits in a Direct Injection Spark Ignition engine, the method comprising operating the engine with a lubricating oil composition comprising:
         (a) a major amount of an oil of lubricating viscosity; and   (b) at least one foam inhibitor selected from the group consisting of silicon oils, polysiloxanes, polyacrylates, and polymethacrylates;
 
wherein the foam inhibitor is not poly (phenyl-methyl) siloxane; and further wherein the amount of said foam inhibitor in said lubricating oil composition is at an effective concentration to achieve at least 10% reduction in intake valve deposits in said Direct Injection Spark Ignition engine compared to operating the engine with said lubricating oil composition without any foam inhibitor.

FIELD OF THE INVENTION

The present invention generally relates to a method for reducing intakevalve deposits in Direct Injection Spark Ignition (DISI) engines. Alsoprovided is a method for reducing intake valve deposits in a DISI engineby top treating an oil of lubricating viscosity with a lubricating oiladditive concentrate.

BACKGROUND OF THE INVENTION

Recently a number of automotive engine manufacturers have introduceddirect injection spark ignition (DISI) engines for gasoline. Suchengines inject gasoline. directly into the combustion chamber of theengine, rather than introducing the gasoline indirectly through theintake manifold by means of, for example, carburetors or port fuelinjectors. Because the gasoline. is injected directly into thecombustion chambers, it enables precise control over the amount of fuelburned and the timing of the injection. One disadvantage of thisapproach, however, is that intake valves of DISI engines are likely toform large amounts of intake valve deposits (“IVD” hereinafter), sincethere is no gasoline at the site of the intake valves to provide depositcontrol additives to combat deposits or deposit precursors. These valvedeposits interfere with valve operation, reduce the efficiency of theengine, and have a negative impact on driveability.

Some patent documents disclose solving the problem of intake valvedeposits in direct injection spark ignition engines by using lubricantformulations.

Konishi, Japanese Patent Publication No. 2003-155492 discloseslubricants containing polybutenyl succinimide, dithio zinc phosphate,phenol and/or amine group ash-free antioxidant and alkaline-earth metalgroup cleaner, and which do not contain viscosity index improvers.

Calder, U.S. Patent Application Publication No. 2004/0198614 discloses amethod of reducing intake valve deposits in a direct injection engine,the method comprising lubricating the engine with a lubricating oilcomposition comprising a base oil mixture, the base oil mixturecomprising (i) a Group III, a Group IV oil, or a mixture thereof, incombination with (ii) a synthetic ester oil, the weight ratio of (i) to(ii) being from about 0.2:1 to about 6:1.

Colucci et al., U.S. Patent Application Publication No. 2004/0231632discloses a method and combustion system for reducing the formation ofintake manifold deposits, such as including intake valve valves, andexhaust valve deposits in combustion engines by delivery of anorganomolybdenum source from the vapor phase of an engine lubricant intoa combustion chamber.

Adams et al., U.S. Patent Application Publication No. 2005/0236301discloses a process to prepare a heavy and a light lubricating base oilfrom a partly isomerized Fischer-Tropsch derived feedstock, thefeedstock having an initial boiling point of below 400 degrees C. and afinal boiling point of above 600 degrees C. by (a) separating thefraction via distillation into a light base oil precursor fraction and aheavy base oil precursor fraction; (b) reducing the pour point of eachseparate base oil precursor fraction via dewaxing; and, (c) isolatingthe desired base oil products from the dewaxed oil fractions as obtainedin step (b).

Wedlock, U.S. Patent Application Publication No. 2006/0052252 disclosesa lubricant composition containing a mixture of at least twoFischer-Tropsch derived base oils and one or more additives wherein oneFischer-Tropsch derived base oil (low viscosity component) has akinematic viscosity at 100.degree. C. of less than 7 cSt and the secondFischer-Tropsch derived base oil (high viscosity component) has akinematic viscosity at 100.degree. C. of more than 18 cSt.

Locke et al., U.S. Patent Application Publication No. 2007/0197406discloses, intake valve deposits in a direct injection internalcombustion engine are reduced by lubricating the engine with a lubricantthat is substantially free of ashless organic friction modifiers andwhose base oil has a Noack volatility of less than 12 mass %.

A number of patent documents disclose the use of foam inhibitors in ageneric manner in gasoline direct injection engines. These include: U.S.Patent Application Publication Nos. 2008/0234153, 2008/0248981 and2008/0110799; and Japanese Patent Publication Nos. 2008-120908,2001-262172, 2008-231192, and 2008-231191.

As described above, intake valve deposits are recognized as a problem inDISI engines. A number of attempts have been made to alleviate theproblem of reducing intake valve deposits in DISI engines.

SUMMARY OF THE INVENTION

One embodiment of the present invention is directed to a method forreducing intake valve deposits in a Direct Injection Spark Ignitionengine, the method comprising operating the engine with a lubricatingoil composition comprising:

-   -   (a) a major amount of an oil of lubricating viscosity; and    -   (b) at least one foam inhibitor selected from the group        consisting of silicon oils, polysiloxanes, polyacrylates, and        polymethacrylates;        wherein the foam inhibitor is not poly(phenylmethyl) siloxane;        and further wherein the amount of said foam inhibitor in said        lubricating oil composition is at an effective concentration to        achieve at least 10% reduction in intake valve deposits in said        Direct Injection Spark Ignition engine compared to operating the        engine with said lubricating oil composition without any foam        inhibitor.

Another embodiment of the present invention is directed to a method forreducing intake valve deposits in a Direct Injection Spark Ignitionengine, the method comprising:

-   -   (a) operating said engine with a lubricating oil; and    -   (b) top treating said lubricating oil composition with a        lubricating oil concentrate comprising at least one foam        inhibitor selected from the group consisting of silicon oils,        polysiloxanes, polyacrylates, and polymethacrylates to therby        provide a top treated lubricating oil composition;        wherein the foam inhibitor is not poly (phenyl-methyl) siloxane;        and further wherein the amount of said foam inhibitor in said        top treated lubricating oil composition is at an effective        concentration to achieve at least 10% reduction in intake valve        deposits in said Direct Injection Spark Ignition engine compared        to operating the engine with the lubricating oil of step (a)        without any top treatment.

In another embodiment, the lubricating oil composition disclosed hereinfurther comprises at least one additive selected from the groupconsisting of antioxidants, antiwear agents, detergents, rustinhibitors, demulsifiers, friction modifiers, extreme pressure agents,viscosity index improvers, pour point depressants, dispersants,corrosion inhibitors, and combinations thereof.

DEFINITIONS

The term “top treating” means adding the lubricating oil concentratedescribed herein to the crankcase oil already present in the DISIengine.

DETAILED DESCRIPTION OF THE INVENTION

Among other factors, the present invention is based on the surprisingdiscovery that the addition of larger than typical amounts of foaminhibiting additives to lubricants used to lubricate direct injectiongasoline engines can substantially decrease the amount of intake valvedeposits in said engines. The typical amount of foam inhibitingadditives used in many lubricants varies from about 5 to about 30 ppmw.The increased amount of added foam inhibitor is quite small, and enablesa large reduction in IVD deposits without the use of expensive specialtylubricants or base oils such as polyalphaolefins (Group IV) or ester(Group V) lubricants. This finding also enables the aftermarket additionof small amounts of foam inhibitor boosters in gasoline direct injectionengines lubricated with conventional lubricants.

In accordance with one embodiment of the present invention, providedherein is a method for reducing intake valve deposits in a DirectInjection Spark Ignition engine, the method comprising operating theengine with a lubricating oil composition comprising:

-   -   (a) a major amount of an oil of lubricating viscosity; and    -   (b) at least one foam inhibitor selected from the group        consisting of silicon oils, polysiloxanes, polyacrylates, and        polymethacrylates;        wherein the foam inhibitor is not poly (pheny-lmethyl) siloxane;        and further wherein the amount of said foam inhibitor in said        lubricating oil composition is at an effective concentration to        achieve at least 10% reduction in intake valve deposits in said        Direct Injection Spark Ignition engine compared to operating the        engine with said lubricating oil composition without any foam        inhibitor.

In accordance with another embodiment of the present invention, providedherein is a method for reducing intake valve deposits in a DirectInjection Spark Ignition engine, the method comprising:

-   -   (a) operating said engine with a lubricating oil; and    -   (b) top treating said lubricating oil with a lubricating oil        concentrate comprising at least one foam inhibitor selected from        the group consisting of silicon oils, polysiloxanes,        polyacrylates, and polymethacrylates to therby provide a top        treated lubricating oil composition;        wherein the foam inhibitor is not poly (phenyl-methyl) siloxane;        and further wherein the amount of said foam inhibitor in said        top treated lubricating oil composition is at an effective        concentration to achieve at least 10% reduction in intake valve        deposits in said Direct Injection Spark Ignition engine compared        to operating the engine with the lubricating oil step (a)        without any top treatment. In one embodiment of the invention        the Direct Injection Spark Ignition engine is an engine that is        equipped with positive crankcase ventilation. Positive crankcase        ventilation is a method for reducing emissions in an engine in        which combustion gases that escape from the combustion chamber        past the piston and piston rings into the crankcase (often        called “blow-by”) are returned through the intake manifold to        the combustion chamber, where the re-circulated hydrocarbons are        burned.

The Oil of Lubricating Viscosity

The oil of lubricating viscosity for use in the lubricating oilcompositions of the present invention, also referred to as a base oil,is typically present therein in a major amount, e.g., an amount ofgreater than 50 wt. %, preferably greater than about 70 wt. %, morepreferably from about 80 to about 99.5 wt. % and most preferably fromabout 85 to about 98 wt. %, based on the total weight of thecomposition. The expression “base oil” as used herein shall beunderstood to mean a base stock or blend of base stocks which is alubricant component that is produced by a single manufacturer to thesame specifications (independent of feed source or manufacturer'slocation); that meets the same manufacturer's specification; and that isidentified by a unique formula, product identification number, or both.

The base oil for use herein can be any presently known orlater-discovered oil of lubricating viscosity used in formulatinglubricating oil compositions for any and all such applications, e.g.,engine oils, marine cylinder oils, functional fluids such as hydraulicoils, gear oils, transmission fluids, etc. The selection of theparticular base oil depends on the contemplated application of thelubricant and the presence of other additives. For example, the oil oflubricating viscosity useful in the practice of the invention may rangein viscosity from light distillate mineral oils to heavy lubricatingoils such as gasoline engine oils, mineral lubricating oils and heavyduty diesel oils. Additionally, the base oils for use herein canoptionally contain viscosity index improvers, e.g., polymericalkylmethacrylates; olefinic copolymers, e.g., an ethylene-propylenecopolymer or a styrene-butadiene copolymer; and the like and mixturesthereof. The lubricating oil compositions of this invention can beprepared by admixing, by conventional techniques, an appropriate amountof the foam inhibitor compounds disclosed herein in an additiveconcentrate with an oil of lubricating viscosity and conventionallubricating oil additives

As one skilled in the art would readily appreciate, the viscosity of thebase oil is dependent upon the application. Accordingly, the viscosityof a base oil for use herein will ordinarily range from about 2 to about2000 centistokes (cSt) at 100° Centigrade (C). Generally, individuallythe base oils used as engine oils will have a kinematic viscosity rangeat 100° C. of about 2 cSt to about 30 cSt, preferably about 3 cSt toabout 16 cSt, and most preferably about 4 cSt to about 12 cSt and willbe selected or blended depending on the desired end use and theadditives in the finished oil to give the desired grade of engine oil,e.g., a lubricating oil composition having an SAE Viscosity Grade of 0W,0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50,5W-60, 10W, 10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30 or15W-40. Oils used as gear oils can have viscosities ranging from about 2cSt to about 2000 cSt at 100° C.

Base stocks may be manufactured using a variety of different processesincluding, but not limited to, distillation, solvent refining, hydrogenprocessing, oligomerization, esterification, and rerefining. Rerefinedstock shall be substantially free from materials introduced throughmanufacturing, contamination, or previous use. The base oil of thelubricating oil compositions of this invention may be any natural orsynthetic lubricating base oil. Suitable hydrocarbon synthetic oilsinclude, but are not limited to, oils prepared from the polymerizationof ethylene or from the polymerization of 1-olefins to provide polymerssuch as polyalphaolefin or PAO oils, or from hydrocarbon synthesisprocedures using carbon monoxide and hydrogen gases such as in aFischer-Tropsch process. For example, a suitable base oil is one thatcomprises little, if any, heavy fraction; e.g., little, if any, lube oilfraction of viscosity 20 cSt or higher at 100° C.

The base oil may be derived from natural lubricating oils, syntheticlubricating oils or mixtures thereof. Suitable base oil includes basestocks obtained by isomerization of synthetic wax and slack wax, as wellas hydrocracked base stocks produced by hydrocracking (rather thansolvent extracting) the aromatic and polar components of the crude.Suitable base oils include those in all API categories I, II, III, IVand V as defined in API Publication 1509, 14th Edition, Addendum I,December 1998. Group IV base oils are polyalphaolefins (PAO). Group Vbase oils include all other base oils not included in Group I, II, III,or IV.

As will be demonstrated herein, an advantage of the present invention isthat low amounts of IVD can be obtained without the use of large amountsof expensive Group IV or Group V basestocks. Accordingly, in oneembodiment of the present invention, the oil of lubricating viscositycomprises at least 50 wt-% of a Group III basestock. In anotherembodiment of the present invention, the oil of lubricating viscositycomprises at least 50 wt-% of an API Group II basestock. In a furtherembodiment of the present invention, the oil of lubricating viscositycomprises at least 50 wt-% of a mixture of Group II and Group IIIbasestocks. In one embodiment of the present invention, the oil oflubricating viscosity does not contain either a Group IV or a Group Vbasestocks. In one embodiment of the present invention, the base oil isa mixture of Group II, Group III, and Group IV basestocks.

Natural oils may also be employed and include mineral lubricating oilssuch as, for example, liquid petroleum oils, solvent-treated oracid-treated mineral lubricating oils of the paraffinic, naphthenic ormixed paraffinic-naphthenic types, oils derived from coal or shale,animal oils, vegetable oils (e.g., rapeseed oils, castor oils and lardoil), and the like. Synthetic lubricating oils may also be employed andinclude, but are not limited to, hydrocarbon oils and halo-substitutedhydrocarbon oils such as polymerized and interpolymerized olefins, e.g.,polybutylenes, polypropylenes, propylene-isobutylene copolymers,chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes),poly(1-decenes), and the like and mixtures thereof; alkylbenzenes suchas dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di(2-ethylhexyl)-benzenes, and the like; polyphenyls such as biphenyls,terphenyls, alkylated polyphenyls, and the like; alkylated diphenylethers and alkylated diphenyl sulfides and the derivative, analogs andhomologs thereof and the like.

Other synthetic lubricating oils employed include, but are not limitedto, oils made by polymerizing olefins of less than 5 carbon atoms suchas ethylene, propylene, butylenes, isobutene, pentene, and mixturesthereof. Methods of preparing such polymer oils are well known to thoseskilled in the art.

Additional synthetic hydrocarbon oils employed include liquid polymersof alpha olefins having the proper viscosity. Especially usefulsynthetic hydrocarbon oils are the hydrogenated liquid oligomers of C₆to C₁₂ alpha olefins such as, for example, 1-decene trimer.

Another class of synthetic lubricating oils include, but are not limitedto, alkylene oxide polymers, i.e., homopolymers, interpolymers, andderivatives thereof where the terminal hydroxyl groups have beenmodified by, for example, esterification or etherification. These oilsare exemplified by the oils prepared through polymerization of ethyleneoxide or propylene oxide, the alkyl and phenyl ethers of thesepolyoxyalkylene polymers (e.g., methyl poly propylene glycol etherhaving an average molecular weight of 1,000, diphenyl ether ofpolyethylene glycol having a molecular weight of 500 to 1000, diethylether of polypropylene glycol having a molecular weight of 1,000 to1,500, etc.) or mono- and polycarboxylic esters thereof such as, forexample, the acetic esters, mixed C₃-C₈ fatty acid esters, or the C₁₃oxo acid diester of tetraethylene glycol.

Yet another class of synthetic lubricating oils include, but are notlimited to, the esters of dicarboxylic acids e.g., phthalic acid,succinic acid, alkyl succinic acids, alkenyl succinic acids, maleicacid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipicacid, linoleic acid dimer, malonic acids, alkyl malonic acids, alkenylmalonic acids, etc., with a variety of alcohols, e.g., butyl alcohol,hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,diethylene glycol monoether, propylene glycol, etc. Specific examples ofthese esters include dibutyl adipate, di(2-ethylhexyl)sebacate,di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecylazelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the2-ethylhexyl diester of linoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid and the like.

Esters may also be employed as synthetic oils and include, but are notlimited to, those made from carboxylic acids having from about 5 toabout 12 carbon atoms with alcohols, e.g., methanol, ethanol, etc.,polyols and polyol ethers such as neopentyl glycol, trimethylol propane,pentaerythritol, dipentaerythritol, tripentaerythritol, and the like.

Silicon-based oils such as, for example, polyalkyl-, polyaryl-,polyalkoxy- or polyaryloxy-siloxane oils and silicate oils, compriseanother class of synthetic lubricating oils which may be employed in thepresent invention. Specific examples of these include, but are notlimited to, tetraethyl silicate, tetra-isopropyl silicate,tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-hexyl) silicate,tetra-(p-tert-butylphenyl) silicate, hexyl-(4-methyl-2-pentoxy)disiloxane, poly (methyl) siloxanes, poly (methylphenyl) siloxanes, andthe like.

The lubricating oil may be derived from unrefined, refined and rerefinedoils, either natural, synthetic or mixtures of two or more of any ofthese of the type disclosed hereinabove. Unrefined oils are thoseobtained directly from a natural or synthetic source (e.g., coal, shale,or tar sands bitumen) without further purification or treatment.Examples of unrefined oils include, but are not limited to, a shale oilobtained directly from retorting operations, a petroleum oil obtaineddirectly from distillation or an ester oil obtained directly from anesterification process, each of which is then used without furthertreatment. Refined oils are similar to the unrefined oils except theyhave been further treated in one or more purification steps to improveone or more properties. These purification techniques are known to thoseof skill in the art and include, for example, solvent extractions,secondary distillation, acid or base extraction, filtration,percolation, hydrotreating, dewaxing, etc. Rerefined oils are obtainedby treating used oils in processes similar to those used to obtainrefined oils. Such rerefined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniquesdirected to removal of spent additives and oil breakdown products.

Lubricating oil base stocks derived from the hydroisomerization of waxmay also be used, either alone or in combination with the aforesaidnatural and/or synthetic base stocks. Such wax isomerate oil is producedby the hydroisomerization of natural or synthetic waxes or mixturesthereof over a hydroisomerization catalyst.

Natural waxes are typically the slack waxes recovered by the solventdewaxing of mineral oils; synthetic waxes are typically the wax producedby the Fischer-Tropsch process.

Foam Inhibitors

A foam inhibitor is a lubricant additive that, when added in smallamounts to a lubricant, either inhibits the formation of foam,accelerates the breaking of foam, or both. At least one foam inhibitoror mixtures thereof is employed in the lubricating oil composition ofthe presently claimed invention. The foam inhibitor employed is selectedfrom the group consisting of silicon oils, polysiloxanes, polyacrylates,polymethacrylates, and combinations thereof, provided that the foaminhibitor may not be poly (phenyl-methyl) siloxane.

In one embodiment, the foam inhibitor is a poly dimethyl siloxane.

In one embodiment, the foam inhibitor is a poly (dimethyl,phenyl-methyl) siloxane. In one embodiment, the foam inhibitor is amixture of poly dimethyl siloxane and poly (dimethyl, phenyl-methyl)siloxane.

In one embodiment, the foam inhibitor is a polymethacrylate.

In one embodiment, the foam inhibitor is a poly (trifluoropropylmethyl)siloxane.

In one embodiment, the amount of the foam inhibitor in the lubricatingoil composition may vary from about 30 to about 500 ppmw, or from about50 to about 500 ppmw, or from about 75 to about 500 ppmw, or from about100 to about 500 ppmw, or from about 150 to about 500 ppmw, or fromabout 200 ppmw to about 400 ppmw, based on the total weight of thelubricating oil composition.

In one embodiment, the reduction in intake valve deposits is at least10%, or at least 20%, or at least 30%, or at least 40%, or at least 50%compared to operating the engine with the lubricating oil compositionwithout any foam inhibitor.

In one embodiment, the amount of the foam inhibitor in the lubricatingoil concentrate may vary from about 0.01 wt. % to about 1 wt. %, fromabout 0.02 wt. % to about 0.8 wt. %, from about 0.03 wt. % to about 0.7wt. %, or from about 0.04 wt. % to about 0.6 wt. %, based on the totalweight of the lubricating oil concentrate. The foam inhibitor can beconveniently added to the lubricating oil concentrate in the form of afoam inhibitor concentrate, which contains the foam inhibitor and atleast one solvent.

Additional Lubricating Oil Additives

The lubricating oil compositions of the present invention may alsocontain other conventional additives for imparting auxiliary functionsto give a finished lubricating oil composition in which these additivesare dispersed or dissolved. For example, the lubricating oilcompositions can be blended with antioxidants, anti-wear agents, ashlessdispersants, detergents, rust inhibitors, dehazing agents, demulsifyingagents, metal deactivating agents, friction modifiers, pour pointdepressants, co-solvents, package compatibilisers, corrosion-inhibitors,dyes, extreme pressure agents and the like and mixtures thereof. Avariety of the additives are known and commercially available. Theseadditives, or their analogous compounds, may be employed for thepreparation of the lubricating oil compositions of the invention by theusual blending procedures.

Examples of antioxidants include, but are not limited to, aminic types,e.g., diphenylamine, phenyl-alpha-napthyl-amine, N,N-di(alkylphenyl)amines; and alkylated phenylene-diamines; phenolics such as, forexample, BHT, sterically hindered alkyl phenols such as2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol and2,6-di-tert-butyl-4-(2-octyl-3-propanoic) phenol; and mixtures thereof.

Examples of antiwear agents include, but are not limited to, zincdialkyldithiophosphates and zinc diaryldithiophosphates, e.g., thosedescribed in an article by Born et al. entitled “Relationship betweenChemical Structure and Effectiveness of some Metallic Dialkyl- andDiaryl-dithiophosphates in Different Lubricated Mechanisms”, appearingin Lubrication Science 4-2 Jan. 1992, see for example pages 97-100; arylphosphates and phosphites, sulfur-containing esters, phosphosulfurcompounds, metal or ash-free dithiocarbamates, xanthates, alkyl sulfidesand the like and mixtures thereof.

Representative examples of ashless dispersants include, but are notlimited to, amines, alcohols, amides, or ester polar moieties attachedto the polymer backbones via bridging groups. An ashless dispersant ofthe present invention may be, for example, selected from oil solublesalts, esters, amino-esters, amides, imides, and oxazolines of longchain hydrocarbon substituted mono and dicarboxylic acids or theiranhydrides; thiocarboxylate derivatives of long chain hydrocarbons, longchain aliphatic hydrocarbons having a polyamine attached directlythereto; and Mannich condensation products formed by condensing a longchain substituted phenol with formaldehyde and polyalkylene polyamine.

Carboxylic dispersants are reaction products of carboxylic acylatingagents (acids, anhydrides, esters, etc.) comprising at least about 34and preferably at least about 54 carbon atoms with nitrogen containingcompounds (such as amines), organic hydroxy compounds (such as aliphaticcompounds including monohydric and polyhydric alcohols, or aromaticcompounds including phenols and naphthols), and/or basic inorganicmaterials. These reaction products include imides, amides, and esters.

Succinimide dispersants are a type of carboxylic dispersant. They areproduced by reacting hydrocarbyl-substituted succinic acylating agentwith organic hydroxy compounds, or with amines comprising at least onehydrogen atom attached to a nitrogen atom, or with a mixture of thehydroxy compounds and amines. The term “succinic acylating agent” refersto a hydrocarbon-substituted succinic acid or a succinic acid-producingcompound, the latter encompasses the acid itself. Such materialstypically include hydrocarbyl-substituted succinic acids, anhydrides,esters (including half esters) and halides.

Succinic-based dispersants have a wide variety of chemical structures.One class of succinic-based dispersants may be represented by theformula:

wherein each R¹ is independently a hydrocarbyl group, such as apolyolefin-derived group. Typically the hydrocarbyl group is an alkylgroup, such as a polyisobutyl group. Alternatively expressed, the R¹groups can contain about 40 to about 500 carbon atoms, and these atomsmay be present in aliphatic forms. R² is an alkylene group, commonly anethylene (C₂H₄) group. Examples of succinimide dispersants include thosedescribed in, for example, U.S. Pat. Nos. 3,172,892, 4,234,435 and6,165,235.

The polyalkenes from which the substituent groups are derived aretypically homopolymers and interpolymers of polymerizable olefinmonomers of 2 to about 16 carbon atoms, and usually 2 to 6 carbon atoms.The amines which are reacted with the succinic acylating agents to formthe carboxylic dispersant composition can be monoamines or polyamines.

Succinimide dispersants are referred to as such since they normallycontain nitrogen largely in the form of imide functionality, althoughthe amide functionality may be in the form of amine salts, amides,imidazolines as well as mixtures thereof. To prepare a succinimidedispersant, one or more succinic acid-producing compounds and one ormore amines are heated and typically water is removed, optionally in thepresence of a substantially inert organic liquid solvent/diluent. Thereaction temperature can range from about 80° C. up to the decompositiontemperature of the mixture or the product, which typically falls betweenabout 100° C. to about 300° C. Additional details and examples ofprocedures for preparing the succinimide dispersants of the presentinvention include those described in, for example, U.S. Pat. Nos.3,172,892, 3,219,666, 3,272,746, 4,234,435, 6,165,235 and 6,440,905.

Suitable ashless dispersants may also include amine dispersants, whichare reaction products of relatively high molecular weight aliphatichalides and amines, preferably polyalkylene polyamines. Examples of suchamine dispersants include those described in, for example, U.S. Pat.Nos. 3,275,554, 3,438,757, 3,454,555 and 3,565,804. Suitable ashlessdispersants may further include “Mannich dispersants,” which arereaction products of alkyl phenols in which the alkyl group contains atleast about 30 carbon atoms with aldehydes (especially formaldehyde) andamines (especially polyalkylene polyamines). Examples of suchdispersants include those described in, for example, U.S. Pat. Nos.3,036,003, 3,586,629. 3,591,598 and 3,980,569.

Suitable ashless dispersants may also be post-treated ashlessdispersants such as post-treated succinimides, e.g., post-treatmentprocesses involving borate or ethylene carbonate as disclosed in, forexample, U.S. Pat. Nos. 4,612,132 and 4,746,446; and the like as well asother post-treatment processes. The carbonate-treated alkenylsuccinimide is a polybutene succinimide derived from polybutenes havinga molecular weight of about 450 to about 3000, preferably from about 900to about 2500, more preferably from about 1300 to about 2400, and mostpreferably from about 2000 to about 2400, as well as mixtures of thesemolecular weights. Preferably, it is prepared by reacting, underreactive conditions, a mixture of a polybutene succinic acid derivative,an unsaturated acidic reagent copolymer of an unsaturated acidic reagentand an olefin, and a polyamine, such as disclosed in U.S. Pat. No.5,716,912, the contents of which are incorporated herein by reference.

Suitable ashless dispersants may also be polymeric, which areinterpolymers of oil-solubilizing monomers such as decyl methacrylate,vinyl decyl ether and high molecular weight olefins with monomerscontaining polar substitutes. Examples of polymeric dispersants includethose described in, for example, U.S. Pat. Nos. 3,329,658; 3,449,250 and3,666,730.

In one preferred embodiment of the present invention, an ashlessdispersant for use in the lubricating oil composition is abis-succinimide derived from a polyisobutenyl group having a numberaverage molecular weight of about 700 to about 2300. The dispersant(s)for use in the lubricating oil compositions of the present invention arepreferably non-polymeric (e.g., are mono- or bis-succinimides).

Generally, the one or more ashless dispersants are present in thelubricating oil composition in an amount ranging from about 0.01 wt. %to about 10 wt. %, based on the total weight of the lubricating oilcomposition.

Representative examples of metal detergents include sulphonates,alkylphenates, sulfurized alkyl phenates, carboxylates, salicylates,phosphonates, and phosphinates. Commercial products are generallyreferred to as neutral or overbased. Overbased metal detergents aregenerally produced by carbonating a mixture of hydrocarbons, detergentacid, for example: sulfonic acid, alkylphenol, carboxylate etc., metaloxide or hydroxides (for example calcium oxide or calcium hydroxide) andpromoters such as xylene, methanol and water. For example, for preparingan overbased calcium sulfonate, in carbonation, the calcium oxide orhydroxide reacts with the gaseous carbon dioxide to form calciumcarbonate. The sulfonic acid is neutralized with an excess of CaO orCa(OH)₂, to form the sulfonate.

Metal-containing or ash-forming detergents function as both detergentsto reduce or remove deposits and as acid neutralizers or rustinhibitors, thereby reducing wear and corrosion and extending enginelife. Detergents generally comprise a polar head with a long hydrophobictail. The polar head comprises a metal salt of an acidic organiccompound. The salts may contain a substantially stoichiometric amount ofthe metal in which case they are usually described as normal or neutralsalts, and would typically have a total base number or TBN (as can bemeasured by ASTM D2896) of from 0 to about 80. A large amount of a metalbase may be incorporated by reacting excess metal compound (e.g., anoxide or hydroxide) with an acidic gas (e.g., carbon dioxide). Theresulting overbased detergent comprises neutralized detergent as theouter layer of a metal base (e.g., carbonate) micelle. Such overbaseddetergents may have a TBN of about 150 or greater, and typically willhave a TBN of from about 250 to about 450 or more.

Detergents that may be used include oil-soluble neutral and overbasedsulfonates, phenates, sulfurized phenates, thiophosphonates,salicylates, and naphthenates and other oil-soluble carboxylates of ametal, particularly the alkali or alkaline earth metals, e.g., barium,sodium, potassium, lithium, calcium, and magnesium. The most commonlyused metals are calcium and magnesium, which may both be present indetergents used in a lubricant, and mixtures of calcium and/or magnesiumwith sodium. Particularly convenient metal detergents are neutral andoverbased calcium sulfonates having TBN of from about 20 to about 450,neutral and overbased calcium phenates and sulfurized phenates havingTBN of from about 50 to about 450 and neutral and overbased magnesium orcalcium salicylates having a TBN of from about 20 to about 450.Combinations of detergents, whether overbased or neutral or both, may beused.

In one embodiment, the detergent can be one or more alkali or alkalineearth metal salts of an alkyl-substituted hydroxyaromatic carboxylicacid. Suitable hydroxyaromatic compounds include mononuclear monohydroxyand polyhydroxy aromatic hydrocarbons having 1 to 4, and preferably 1 to3, hydroxyl groups. Suitable hydroxyaromatic compounds include phenol,catechol, resorcinol, hydroquinone, pyrogallol, cresol, and the like.The preferred hydroxyaromatic compound is phenol.

The alkyl substituted moiety of the alkali or alkaline earth metal saltof an alkyl-substituted hydroxyaromatic carboxylic acid is derived froman alpha olefin having from about 10 to about 80 carbon atoms. Theolefins employed may be linear, isomerized linear, branched or partiallybranched linear. The olefin may be a mixture of linear olefins, amixture of isomerized linear olefins, a mixture of branched olefins, amixture of partially branched linear or a mixture of any of theforegoing.

In one embodiment, the mixture of linear olefins that may be used is amixture of normal alpha olefins selected from olefins having from about12 to about 30 carbon atoms per molecule. In one embodiment, the normalalpha olefins are isomerized using at least one of a solid or liquidcatalyst.

In another embodiment, the olefins are a branched olefinic propyleneoligomer or mixture thereof having from about 20 to about 80 carbonatoms, i.e., branched chain olefins derived from the polymerization ofpropylene. The olefins may also be substituted with other functionalgroups, such as hydroxy groups, carboxylic acid groups, heteroatoms, andthe like. In one embodiment, the branched olefinic propylene oligomer ormixtures thereof have from about 20 to about 60 carbon atoms. In oneembodiment, the branched olefinic propylene oligomer or mixtures thereofhave from about 20 to about 40 carbon atoms.

In one embodiment, at least about 75 mole % (e.g., at least about 80mole %, at least about 85 mole %, at least about 90 mole %, at leastabout 95 mole %, or at least about 99 mole %) of the alkyl groupscontained within the alkali or alkaline earth metal salt of analkyl-substituted hydroxyaromatic carboxylic acid such as the alkylgroups of an alkaline earth metal salt of an alkyl-substitutedhydroxybenzoic acid detergent are a C₂₀ or higher. In anotherembodiment, the alkali or alkaline earth metal salt of analkyl-substituted hydroxyaromatic carboxylic acid is an alkali oralkaline earth metal salt of an alkyl-substituted hydroxybenzoic acidthat is derived from an alkyl-substituted hydroxybenzoic acid in whichthe alkyl groups are the residue of normal alpha-olefins containing atleast 75 mole % C₂₀ or higher normal alpha-olefins.

In another embodiment, at least about 50 mole % (e.g., at least about 60mole %, at least about 70 mole %, at least about 80 mole %, at leastabout 85 mole %, at least about 90 mole %, at least about 95 mole %, orat least about 99 mole %) of the alkyl groups contained within thealkali or alkaline earth metal salt of an alkyl-substitutedhydroxyaromatic carboxylic acid such as the alkyl groups of an alkali oralkaline earth metal salt of an alkyl-substituted hydroxybenzoic acidare about C₁₄ to about C₁₈.

The resulting alkali or alkaline earth metal salt of analkyl-substituted hydroxyaromatic carboxylic acid will be a mixture ofortho and para isomers. In one embodiment, the product will containabout 1 to 99% ortho isomer and 99 to 1% para isomer. In anotherembodiment, the product will contain about 5 to 70% ortho and 95 to 30%para isomer.

The alkali or alkaline earth metal salts of an alkyl-substitutedhydroxyaromatic carboxylic acid can be neutral or overbased. Generally,an overbased alkali or alkaline earth metal salt of an alkyl-substitutedhydroxyaromatic carboxylic acid is one in which the BN of the alkali oralkaline earth metal salts of an alkyl-substituted hydroxyaromaticcarboxylic acid has been increased by a process such as the addition ofa base source (e.g., lime) and an acidic overbasing compound (e.g.,carbon dioxide).

Overbased salts may be low overbased, e.g., an overbased salt having aBN below about 100. In one embodiment, the BN of a low overbased saltmay be from about 5 to about 50. In another embodiment, the BN of a lowoverbased salt may be from about 10 to about 30. In yet anotherembodiment, the BN of a low overbased salt may be from about 15 to about20.

Overbased detergents may be medium overbased, e.g., an overbased salthaving a BN from about 100 to about 250. In one embodiment, the BN of amedium overbased salt may be from about 100 to about 200. In anotherembodiment, the BN of a medium overbased salt may be from about 125 toabout 175.

Overbased detergents may be high overbased, e.g., an overbased salthaving a BN above about 250. In one embodiment, the BN of a highoverbased salt may be from about 250 to about 450.

Sulfonates may be prepared from sulfonic acids which are typicallyobtained by the sulfonation of alkyl substituted aromatic hydrocarbonssuch as those obtained from the fractionation of petroleum or by thealkylation of aromatic hydrocarbons. Examples included those obtained byalkylating benzene, toluene, xylene, naphthalene, diphenyl or theirhalogen derivatives. The alkylation may be carried out in the presenceof a catalyst with alkylating agents having from about 3 to more than 70carbon atoms. The alkaryl sulfonates usually contain from about 9 toabout 80 or more carbon atoms, preferably from about 16 to about 60carbon atoms per alkyl substituted aromatic moiety.

The oil soluble sulfonates or alkaryl sulfonic acids may be neutralizedwith oxides, hydroxides, alkoxides, carbonates, carboxylate, sulfides,hydrosulfides, nitrates, borates and ethers of the metal. The amount ofmetal compound is chosen having regard to the desired TBN of the finalproduct but typically ranges from about 100 to about 220 wt. %(preferably at least about 125 wt. %) of that stoichiometricallyrequired.

Metal salts of phenols and sulfurized phenols are prepared by reactionwith an appropriate metal compound such as an oxide or hydroxide andneutral or overbased products may be obtained by methods well known inthe art. Sulfurized phenols may be prepared by reacting a phenol withsulfur or a sulfur containing compound such as hydrogen sulfide, sulfurmonohalide or sulfur dihalide, to form products which are generallymixtures of compounds in which 2 or more phenols are bridged by sulfurcontaining bridges.

Generally, the one or more detergents are present in the lubricating oilcomposition in an amount ranging from about 0.01 wt. % to about 10 wt.%, based on the total weight of the lubricating oil composition.

Examples of rust inhibitors include, but are not limited to, nonionicpolyoxyalkylene agents, e.g., polyoxyethylene lauryl ether,polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether,polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate,polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate;stearic acid and other fatty acids; dicarboxylic acids; metal soaps;fatty acid amine salts; metal salts of heavy sulfonic acid; partialcarboxylic acid ester of polyhydric alcohol; phosphoric esters;(short-chain) alkenyl succinic acids; partial esters thereof andnitrogen-containing derivatives thereof; synthetic alkarylsulfonates,e.g., metal dinonylnaphthalene sulfonates; and the like and mixturesthereof.

Examples of friction modifiers include, but are not limited to,alkoxylated fatty amines; borated fatty epoxides; fatty phosphites,fatty epoxides, fatty amines, borated alkoxylated fatty amines, metalsalts of fatty acids, fatty acid amides, glycerol esters, boratedglycerol esters; and fatty imidazolines as disclosed in U.S. Pat. No.6,372,696, the contents of which are herein incorporated by reference;friction modifiers obtained from a reaction product of a C₄ to C₇₅,preferably a C₆ to C₂₄, and most preferably a C₆ to C₂₀, fatty acidester and a nitrogen-containing compound selected from the groupconsisting of ammonia, and an alkanolamine and the like and mixturesthereof.

Examples of a pour point depressant include, but are not limited to,polymethacrylates, alkyl acrylate polymers, alkyl methacrylate polymers,di(tetra-paraffin phenol)phthalate, condensates of tetra-paraffinphenol, condensates of a chlorinated paraffin with naphthalene andcombinations thereof. In one embodiment, a pour point depressantcomprises an ethylene-vinyl acetate copolymer, a condensate ofchlorinated paraffin and phenol, polyalkyl styrene and the like andcombinations thereof. The amount of the pour point depressant may varyfrom about 0.01 wt. % to about 10 wt. %.

Examples of a demulsifier include, but are not limited to, anionicsurfactants (e.g., alkyl-naphthalene sulfonates, alkyl benzenesulfonates and the like), nonionic alkoxylated alkylphenol resins,polymers of alkylene oxides (e.g., polyethylene oxide, polypropyleneoxide, block copolymers of ethylene oxide, propylene oxide and thelike), esters of oil soluble acids, polyoxyethylene sorbitan ester andthe like and combinations thereof. The amount of the demulsifier mayvary from about 0.01 wt. % to about 10 wt. %.

Examples of a corrosion inhibitor include, but are not limited to, halfesters or amides of dodecylsuccinic acid, phosphate esters,thiophosphates, alkyl imidazolines, sarcosines and the like andcombinations thereof. The amount of the corrosion inhibitor may varyfrom about 0.01 wt. % to about 5 wt. %.

Examples of an extreme pressure agent include, but are not limited to,sulfurized animal or vegetable fats or oils, sulfurized animal orvegetable fatty acid esters, fully or partially esterified esters oftrivalent or pentavalent acids of phosphorus, sulfurized olefins,dihydrocarbyl polysulfides, sulfurized Diels-Alder adducts, sulfurizeddicyclopentadiene, sulfurized or co-sulfurized mixtures of fatty acidesters and monounsaturated olefins, co-sulfurized blends of fatty acid,fatty acid ester and alpha-olefin, functionally-substituteddihydrocarbyl polysulfides, thia-aldehydes, thia-ketones, epithiocompounds, sulfur-containing acetal derivatives, co-sulfurized blends ofterpene and acyclic olefins, and polysulfide olefin products, aminesalts of phosphoric acid esters or thiophosphoric acid esters and thelike and combinations thereof. The amount of the extreme pressure agentmay vary from about 0.01 wt. % to about 5 wt. %.

Each of the foregoing additives, when used, is used at a functionallyeffective amount to impart the desired properties to the lubricant.Thus, for example, if an additive is a friction modifier, a functionallyeffective amount of this friction modifier would be an amount sufficientto impart the desired friction modifying characteristics to thelubricant. Generally, the concentration of each of these additives, whenused, may range, unless otherwise specified, from about 0.001% to about20% by weight, and in one embodiment about 0.01% to about 10% by weightbased on the total weight of the lubricating oil composition.

In another embodiment of the invention, the lubricating oil additives ofthe present invention may be provided as an additive package orconcentrate in which the additives are incorporated into a substantiallyinert, normally liquid organic diluent such as, for example, mineraloil, naphtha, benzene, toluene or xylene to form an additiveconcentrate.

Concentrates and Diluents

Lubricating oil concentrates are also contemplated herein. Theseconcentrates usually include at least from about 90 wt. % to about 10wt. %, or from about 80 wt. % to about 20 wt. %, or from about 70 wt. %to about 30 wt. %, or from about 60 wt. % to about 40 wt. % of a diluentoil, and from about 10 wt. % to about 90 wt. %, or from about 20 wt. %to about 80 wt. %, or from about 30 wt. % to about 70 wt. %, or fromabout 40 wt. % to about 60 wt. %, of the foam inhibitor described in thelubricating oil composition of the present invention, or combinationsthereof. Typically, the concentrates contain sufficient diluent to makethem easy to handle during shipping and storage. Suitable diluents forthe concentrates include any inert diluent, preferably an oil oflubricating viscosity, so that the concentrate may be readily mixed withlubricating oils to prepare lubricating oil compositions. Suitablelubricating oils that may be used as diluents typically have viscosityin the range from about 35 to about 500 Saybolt Universal Seconds (SUS)at 100° F. (38° C.), although any oil of lubricating viscosity may beused.

If desired, other additives can be admixed with the foregoinglubricating oil concentrate to enhance performance. Examples of theseadditives include, but are not limited to antioxidants, antiwear agents,detergents, rust inhibitors, demulsifiers, friction modifiers, extremepressure agents, viscosity index improvers, pour point depressants,dispersants, corrosion inhibitors, and the like, at the usual levels inaccordance with well known practice.

It is also contemplated that the foam inhibitors of the presentinvention, along with other additional additives described herein, maybe employed as a top treatment for crankcase lubricants employed in DISIengines. When so employed, the top treatment lubricating oil concentratemay be added at from about 0.01 to 5% by weight to the oil, or fromabout 0.5 to about 2% by weight to the oil, based on the total weight ofthe lubricant composition.

In another embodiment, the top treatment lubricating oil concentrate isadded to the original DISI engine lubricating oil composition in anamount such that the final concentration of the foam inhibitor of thepresent invention is between 150 and 500 ppmw, and preferably between200 and 400 ppmw, based on the total weight of the lubricant oilcomposition in the engine.

In one embodiment, the addition of the top treatment lubricating oilconcentrate results in at least a 10% reduction in IVD compared tooperating the engine with a lubricating oil without any top treatmentlubricating oil concentrate.

In one embodiment, the addition of the top treatment lubricating oilconcentrate results in at least a 20% reduction in IVD compared tooperating the engine with a lubricating oil without any top treatmentlubricating oil concentrate.

In one embodiment, the addition of the top treatment lubricating oilconcentrate results in at least a 30% reduction in IVD compared tooperating the engine with a lubricating oil without any top treatmentlubricating oil concentrate.

In one embodiment, the addition of the top treatment lubricating oilconcentrate results in at least a 40% reduction in IVD compared tooperating the engine with a lubricating oil without any top treatmentlubricating oil concentrate.

In one embodiment, the addition of the top treatment lubricating oilconcentrate results in at least a 50% reduction in IVD compared tooperating the engine with a lubricating oil without any top treatmentlubricating oil concentrate.

Performance Testing

The lubricating oil compositions of Examples 1 and 2 below wereevaluated using the 2001 Mitsubishi 1.8 L DISI 212 hour Intake ValveDeposit Test (“Mitsubishi IVD Test”), described hereinafter. The 2001Mitsubishi 1.8 L DISI engine used in this procedure is mounted on anengine stand and connected to a dynamometer with load and speed control.The Mitsubishi DISI engine is a wall guided engine with capability torun both homogenous and lean-stratified combustion. For carrying out thetests described herein, the engine was run on a lean-stratifiedcombustion mode. The engine is first flushed with the oil to be tested,refilled with test oil, and then operated for 30 minutes running at thetest cycle. The engine is then stopped, the oil drained, and a freshsample of test oil is added to the engine. The 212 hr test is thenstarted, which consists of approximately 636 repeats of the test cycle.In the test cycle the engine is operated for 1 minute at idle speed(750+−150 rpm) and no load, followed by 19 minutes of operation at lowload (20.0 N/m) and low speed (1400+−10 rpm). At 106 hours the engine isstopped, and the oil level checked, and if necessary additional test oilis added to the full mark.

After 212 hours, the engine head is removed and the intake valves aswell as the combustion chamber are rated for the deposit weights. Theeight intake valves (two per cylinder) in the engine are rinsed usinghexane and weighed. Intake valves are weighed before and after the testand the difference in weight represent the weight of the depositaccumulated during the test.

EXAMPLES

The following non-limiting examples are illustrative of the presentinvention. The efficacy of the use of high concentrations of foaminhibitor crankcase lubricants for direct injection spark ignitionengines was demonstrated by means of the 2001 Mitsubishi 1.8 L DISI 212hour Intake Valve Deposit Test (the “Mitsubishi IVD Test”), describedabove. All lubricants tested contained identical amounts of additives ofthe “baseline additive package” which includes dispersant, detergents,zinc dialkyldithiophosphate, aminic antioxidant, friction modifier,polymethacrylate pour point depressant, and olefin copolymer viscosityindex improver, but no foam inhibitor additive.

Group III Lubricants Containing Silicone Foam Inhibitor

Mitsubishi IVD Tests were performed on lubricants containing thebaseline additive package in approximately 75 wt-% Yubase 4 Group IIIbase oil and varying active ingredient concentrations of different foaminhibitors. Foam Inhibitor A was a poly (phenyl-methyl) siloxane; B amixture of poly dimethyl siloxane and poly (dimethyl,phenyl-methyl)siloxane; C a polymethacrylate; D a poly (trifluoropropylmethyl)siloxane; and E a poly (dimethyl,phenyl-methyl) siloxane. The resultsare shown in Table 1 below.

TABLE 1 Comparative Comparative Example 1 Example 2 Example 1 Example 2Example 3 Example 4 Example 5 Example 6 Foam inhibitor None A B B B C DE Foam Inhibitor 0 200 30 200 350 300 50 350 concentration, ppmw IVD,average mg 141 150 85 38 52 89 122 105 % IVD NA NA 40 73 63 37 13 25Reduction

The results in Table 1 show the surprising effectiveness of differentfoam inhibitors in reducing intake valve deposits in Group IIIlubricants.

Group II/Group III/Group IV Lubricants Containing Silicone FoamInhibitor

Mitsubishi IVD Tests were performed on lubricants containing thebaseline additive package in approximately 75 wt-% of a mixturecontaining (1) 50 wt-% PT 100D Group II base oil, (2) 30 wt-% Yubase 6group III base oil, and (3) 20 wt-% PAO 8 Group IV base oil, and varyingactive ingredient concentrations of foam inhibitor B from above. Theresults are shown in Table 2 below.

TABLE 2 Example 7 Example 8 Foam inhibitor B B Foam Inhibitor 30 150concentration, ppmw IVD, average mg 38 26

The results in Table 2 show that mixed Group II/Group III/Group IVlubricants containing a foam inhibitor of the invention also exhibit lowamounts of intake valve deposits.

BMW 5W30 Lubricating Oil Top Treated with Foam Inhibitor

Mitsubishi IVD Tests were performed on a commercial 5W30 lubricating oilwhich was top treated with 350 ppm active ingredient concentration offoam inhibitor B from above. The results are shown in Table 3 below.

TABLE 3 Comparative Example 4 Example 4 Baseline 5W30 Baseline Oil + 350ppmw 5W30 Oil Foam Inhibitor B IVD, average mg 95 49 % IVD Reduction NA48

The results in Table 3 show the surprising effectiveness in reducingintake valve deposits of top treating a lubricating oil with aconcentrate containing foam inhibitor.

1. A method for reducing intake valve deposits in a Direct InjectionSpark Ignition engine, the method comprising operating the engine with alubricating oil composition comprising: (a) a major amount of an oil oflubricating viscosity; and (b) at least one foam inhibitor selected fromthe group consisting of silicon oils, polysiloxanes, polyacrylates, andpolymethacrylates; wherein the foam inhibitor is not poly(phenyl-methyl) siloxane; and further wherein the amount of said foaminhibitor in said lubricating oil composition is at an effectiveconcentration to achieve at least 10% reduction in intake valve depositsin said Direct Injection Spark Ignition engine compared to operating theengine with said lubricating oil composition without any foam inhibitor.2. The method of claim 1 wherein the foam inhibitor is selected frompolysiloxanes and polymethacrylates.
 3. The method of claim 1 whereinthe foam inhibitor is selected from the group consisting of:polydimethyl siloxane, poly (dimethyl, phenyl-methyl) siloxane, poly(trifluoropropylmethyl) siloxane, and a mixture of polydimethyl siloxaneand poly (dimethyl, phenyl-methyl) siloxane.
 4. The method of claim 3wherein the foam inhibitor is polydimethyl siloxane.
 5. The method ofclaim 3 wherein the foam inhibitor is poly (dimethyl, phenyl-methyl)siloxane.
 6. The method of claim 3 wherein the foam inhibitor is poly(trifluoropropylmethyl) siloxane.
 7. The method of claim 3 wherein thefoam inhibitor is a mixture of polydimethyl siloxane and poly (dimethyl,phenyl-methyl) siloxane.
 8. The method of claim 1 wherein theconcentration of said foam inhibitor in said lubricating oil compositionis from about 30 to about 500 ppmw.
 9. The method of claim 1 wherein theconcentration of said foam inhibitor in said lubricating oil compositionis from about 100 to about 500 ppmw.
 10. The method of claim 1 whereinthe concentration of said foam inhibitor in said lubricating oilcomposition is from about 150 to about 500 ppmw.
 11. The method of claim1 wherein the concentration of said foam inhibitor in said lubricatingoil composition is from about 200 to about 400 ppmw.
 12. The method ofclaim 1 wherein the reduction of intake valve deposits is at least 20%.13. The method of claim 1 wherein the reduction of intake valve depositsis at least 30%.
 14. The method of claim 1 wherein the reduction ofintake valve deposits is at least 40%.
 15. The method of claim 1 whereinthe reduction of intake valve deposits is at least 50%.
 16. The methodof claim 1 wherein said lubricating oil composition further comprises atleast one additive selected from the group consisting of: detergents,dispersants, antioxidants, ant-wear agents, rust inhibitors, dehazingagents, demulsifying agents, metal deactivating agents, frictionmodifiers, pour point depressants, co-solvents, package compatibilisers,corrosion inhibitors, dyes, extreme pressure agents, and mixturesthereof.
 17. The method of claim 1 wherein said oil of lubricatingviscosity comprises at least 50 wt-% of an API Group II or a Group IIIbase stock, or mixtures thereof.
 18. A method for reducing intake valvedeposits in a Direct Injection Spark Ignition engine, the methodcomprising: (a) operating said engine with a lubricating oil; (b) toptreating said lubricating oil with a lubricating oil concentratecomprising at least one foam inhibitor selected from the groupconsisting of silicon oils, polysiloxanes, polyacrylates, andpolymethacrylates to thereby provide a top treated lubricating oilcomposition; wherein the foam inhibitor is not poly (phenyl-methyl)siloxane; and further wherein the amount of said foam inhibitor in saidtop treated lubricating oil composition is at an effective concentrationto achieve at least 10% reduction in intake valve deposits in saidDirect Injection Spark Ignition engine compared to operating the enginewith the lubricating oil in step (a) without any top treatment.
 19. Themethod of claim 18 wherein the foam inhibitor is selected fromplysiloxanes and polymethacrylates.
 20. The method of claim 18 whereinthe foam inhibitor is selected from the group consisting of:polydimethyl siloxane, poly (dimethyl, phenyl-methyl) siloxane, poly(trifluoropropylmethyl) siloxane, and a mixture of polydimethyl siloxaneand poly (dimethyl, phenyl-methyl) siloxane.
 21. The method of claim 18wherein the foam inhibitor is polydimethyl siloxane.
 22. The method ofclaim 18 wherein the foam inhibitor is poly (dimethyl, phenyl-methyl)siloxane.
 23. The method of claim 18 wherein the foam inhibitor is poly(trifluoropropylmethyl) siloxane.
 24. The method of claim 18 wherein thefoam inhibitor is a mixture of polydimethyl siloxane and poly (dimethyl,phenyl-methyl) siloxane.
 25. The method of claim 18 wherein theconcentration of said foam inhibitor in said lubricating oil concentrateis from about 0.01 to about 1.0 wt-%.
 26. The method of claim 18 whereinthe concentration of said foam inhibitor in said lubricating oilconcentrate is from about 0.02 to about 0.8 wt-%.
 27. The method ofclaim 18 wherein the concentration of said foam inhibitor in saidlubricating oil concentrate is from about 0.03 to about 0.7 wt-%. 28.The method of claim 18 wherein the concentration of said foam inhibitorin said lubricating oil concentrate is from about 0.04 to about 0.6wt-%.
 29. The method of claim 18 wherein the final concentration of saidfoam inhibitor in said top treated lubricating oil composition is fromabout 30 to about 500 ppmw.
 30. The method of claim 18 wherein the finalconcentration of said foam inhibitor in said top treated lubricating oilcomposition is from about 100 to about 500 ppmw.
 31. The method of claim18 wherein the final concentration of said foam inhibitor in said toptreated lubricating oil composition is from about 150 to about 500 ppmw.32. The method of claim 18 wherein the final concentration of said foaminhibitor in said top treated lubricating oil composition is from about200 to about 400 ppmw.
 33. The method of claim 18 wherein the reductionof intake valve deposits is at least 20%.
 34. The method of claim 18wherein the reduction of intake valve deposits is at least 30%.
 35. Themethod of claim 18 wherein the reduction of intake valve deposits is atleast 40%.
 36. The method of claim 18 wherein the reduction of intakevalve deposits is at least 50%.
 37. The method of claim 18 wherein saidtop treated lubricating oil composition further comprises at least oneadditive selected from the group consisting of: detergents, dispersants,antioxidants, ant-wear agents, rust inhibitors, dehazing agents,demulsifying agents, metal deactivating agents, friction modifiers, pourpoint depressants, co-solvents, package compatibilisers, corrosioninhibitors, dyes, extreme pressure agents, and mixtures thereof.
 38. Themethod of claim 18 wherein said lubricating oil comprises at least 50wt-% of an API Group II or a Group III base stock, or mixtures thereof.